The basic configuration of two flagella appears in multiple lineages by convergent evolution, e.g. in
the naked green alga Spermatozopsis [1]}, in gametes of the seaweed
Ulva [2]}, and in swarm cells of Myxomycetes [3]}.
CR exemplifies the isokont condition.
Cells ovoid, \(\sim 5\,\mu \) m radius, have flagella \(\sim 1.5\times \)  body-length and distinguishable by BB age.
During cell division each daughter retains one BB from the mother [4]} which becomes associated with the
trans-flagellum, while a second is assembled localizing near the eyespot and associates with the cis-flagellum
(Fig. REF B,D).
When both flagella prescribe identical beats a nearly-planar breaststroke results, which is highly recurrent and stable to
perturbations [5]}.
Yet despite extensive research [6]}, [7]}, [8]}, [9]}, [10]}
exactly how this IP breatstroke is achieved has remained elusive;
coupling of the flagella pair may be by i) hydrodynamics, ii) drag-based feedback due to cell-body rocking, or iii) intracellular means.
